[HBASE-22031] Provide RSGroupInfo with a new constructor using shallow copy

• Type: Improvement
• Status: Patch Available
• Priority: Minor
• Resolution: Unresolved
• Component/s: rsgroup
• Assignee: Xiang Li
• Reporter: Xiang Li
• Created: 11/Mar/19 14:45
• Updated: 29/Mar/19 08:25

Description

As for org.apache.hadoop.hbase.rsgroup.RSGroupInfo, the following constructor performs deep copies on both servers and tables inputed.

hbase-common/src/main/java/org/apache/hadoop/hbase/rsgroup/RSGroupInfo.java.java

RSGroupInfo(String name, SortedSet<Address> servers, SortedSet<TableName> tables) {
  this.name = name;
  this.servers = (servers == null) ? new TreeSet<>() : new TreeSet<>(servers);
  this.tables  = (tables  == null) ? new TreeSet<>() : new TreeSet<>(tables);
}

The constructor of TreeSet is heavy and I think it is better to have a new constructor with shallow copy and it could be used at least in

hbase-rsgroup/src/main/java/org/apache/hadoop/hbase/rsgroup/RSGroupInfoManagerImpl.java

private synchronized void refresh(boolean forceOnline) throws IOException {
  ...
  groupList.add(new RSGroupInfo(RSGroupInfo.DEFAULT_GROUP, getDefaultServers(), orphanTables));
  ...

It is not needed to allocate new TreeSet to deep copy the output of getDefaultServers() and orphanTables, both of which are allocated in the near context and not updated in the code followed. So it is safe to make a shadow copy here.